Dental appliance

ABSTRACT

A method of producing a positioning guide for an orthodontic bracket is provided. The method includes determining and fixing a position of the orthodontic bracket in relation to a side surface of a corresponding tooth of a setup dental model, wherein the setup dental model has a dentition state of the patient&#39;s dental arch after orthodontic treatment; forming a rigid guiding structure with a first part covering the outer surface of each orthodontic bracket and a second part covering the occlusal surface of the corresponding tooth; and forming a flexible linking structure to connect the first part and the second part of the rigid guiding structure to obtain the positioning guide for the respective orthodontic bracket, wherein the rigid guiding structure is inflexible and the flexible linking structure is elastic and retains form.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a Divisional of U.S. application Ser. No.16/734,253, filed on Jan. 3, 2020, which claims the benefit of U.S.Provisional Patent Application No. 62/788,232, filed Jan. 4, 2019, theentirety of which is incorporated by reference herein.

BACKGROUND OF THE INVENTION Field of the Invention

The present application relates to an indirect bonding method oforthodontic brackets, and in particular to a method of producing apositioning guide used for bonding an orthodontic bracket to each toothof a patient.

Description of the Related Art

In an orthodontic treatment, orthodontic brackets are commonly bonded toeach tooth individually, and an orthodontic archwire placed adjacent tothe lower or upper dental arch connects the orthodontic brackets on thedental arch to induce force on the teeth through the orthodonticbrackets, thereby aligning the teeth with the pre-shaped form of theorthodontic archwire. It is very important to install the orthodonticbrackets at proper positions in order to obtain the ideal treatmenteffect.

In order to more accurately determine an installing position of anorthodontic bracket, a method called an indirect bonding method has beenemployed. In an indirect bonding method, a dentist makes a positioningguide having the shape of a patient's dentition. A set of orthodonticbrackets are releasably attached to the positioning guide. When thepatient is ready, the bonding surfaces of the orthodontic bracketsand/or the tooth surfaces are coated with adhesive. The positioningguide is then placed in the patient's mouth and pressed over thepatient's teeth until the adhesive cures. The positioning guide is thenremoved from the mouth, while the orthodontic brackets remain firmlybonded to the tooth surfaces. Thus, the orthodontic brackets aretransferred from the positioning guide and become bonded to the toothsurfaces at their desired positions. The conventional positioning guideis typically made of a flexible polymer material (e.g., EVA resin) only.

Although existing indirect bonding methods have been adequate for theirintended purposes, they have not been entirely satisfactory in allrespects. For example, a problem which may occur is that the installingposition of the orthodontic bracket easily deviates when transferringthe positioning guide. Therefore, there is a need for an improvedindirect bonding method to facilitate precise and easy positioning oforthodontic brackets.

BRIEF SUMMARY OF THE INVENTION

In accordance with some embodiments of the invention, a method ofproducing a positioning guide used for bonding an orthodontic bracket toa tooth of a patient is provided. The method includes determining andfixing a position of the orthodontic bracket in relation to a sidesurface of a corresponding tooth of a setup dental model, wherein thesetup dental model has a dentition state of the patient's dental archafter orthodontic treatment. The method also includes forming a rigidguiding structure with a first part covering a part of the outer surfaceof the orthodontic bracket and a second part covering the occlusalsurface of the corresponding tooth of the setup dental model, whereinthe first part and the second part of the rigid guiding structure areseparated. In addition, the method includes forming a flexible linkingstructure to connect the first part and the second part of the rigidguiding structure to obtain the positioning guide for the orthodonticbracket. The rigid guiding structure is inflexible and the flexiblelinking structure is elastic and retains form.

In some embodiments, the second part of the rigid guiding structureincludes a handle portion having a greater thickness than the otherportions of the second part. The method further includes forming apositioning guide unit by transferring a plurality of the orthodonticbrackets integrated with the respective positioning guide to an originaldental model reproducing the dentition state of the patient's dentalarch before orthodontic treatment. In addition, the method includesjoining a number of the adjacent positioning guides at the handleportions using at least one holding part.

In some embodiments, the at least one holding part and the rigid guidingstructure comprises the same material.

In some embodiments, the rigid guiding structure comprises aphotopolymerizable material, and the formation of the rigid guidingstructure comprises curing the photopolymerizable material via lightenergy. The photopolymerizable material comprises DURALAY™ resin, dentaltray resin, or the like.

In some embodiments, the flexible linking structure comprises aphotopolymerizable material, and the formation of the flexible linkingstructure comprises curing the photopolymerizable material via lightenergy. The photopolymerizable material comprises ethylene vinyl acetate(EVA) resin or the like.

In some embodiments, the flexible linking structure is formed on theside surface of the corresponding tooth of the setup dental model.

In some embodiments, the second part of the rigid guiding structurefurther extends to cover a part of a second side surface, opposite tothe side surface, of the corresponding tooth of the setup dental model.The flexible linking structure further has a portion formed in thesecond part on the second side surface.

In some embodiments, the method further includes forming a rigid linkingstructure adjacent to the flexible linking structure to connect thefirst part and the second part of the rigid guiding structure. The rigidlinking structure is harder than the flexible linking structure.

In some embodiments, the rigid linking structure and the rigid guidingstructure comprise the same material.

In accordance with some embodiments of the invention, a dental applianceis also provided. The dental appliance includes an orthodontic bracketand a positioning guide configured to position the orthodontic bracketon a tooth of the patient. The orthodontic bracket has a bonding surfacefor adhering to tooth. The positioning guide includes a rigid guidingstructure and a flexible linking structure. The rigid guiding structureincludes a first part and a second part separated from each other. Thefirst part is configured to cover a part of an outer surface of theorthodontic bracket opposite to the bonding surface. The second part hasa shape matching the occlusal surface of the tooth. The flexible linkingstructure is configured to connect the first part and the second part ofthe rigid guiding structure. The rigid guiding structure is inflexibleand the flexible linking structure is flexible and retains elasticity.

In some embodiments, the second part of the rigid guiding structureincludes a handle portion having a greater thickness than the otherportions of the second part.

In some embodiments, the dental appliance further includes a pluralityof the orthodontic brackets, a plurality of the positioning guides, andat least one holding part configured to integrate a number of theadjacent positioning guides at the handle portions.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention can be more fully understood by reading the subsequentdetailed description and examples with references made to theaccompanying drawings, wherein:

FIG. 1 is a simplified flow chart of an indirect bonding method, inaccordance with some embodiments.

FIG. 2 is schematic top views of an original dental model and a setupdental model of a dental arch of a patient, in accordance with someembodiments.

FIG. 3 is a schematic side view of an orthodontic bracket, in accordancewith some embodiments.

FIG. 4 is a schematic side view showing an orthodontic bracket beingbonded to the tongue side surface of a tooth of the setup dental modelin FIG. 2 , in accordance with some embodiments.

FIG. 5 is a schematic side view showing the formation of a rigid guidingstructure consisting of two separated parts, in accordance with someembodiments.

FIG. 6 is a schematic side view showing the formation of a flexiblelinking structure for integrating the two parts of the rigid guidingstructure, in accordance with some embodiments.

FIG. 6A is a schematic side view showing the flexible linking structurebeing formed on tongue and cheek side surfaces of the tooth, inaccordance with some embodiments.

FIG. 7 is a schematic side view showing the formation of a rigid linkingstructure for integrating the two parts of the rigid guiding structure,in accordance with some embodiments.

FIG. 8 is a schematic top view showing the formation of severalpositioning guide units, in accordance with some embodiments.

FIG. 9 is a schematic side view showing that the positioning guide isremoved after the orthodontic bracket is bonded to an actual tooth ofthe patient, in accordance with some embodiments.

DETAILED DESCRIPTION OF THE INVENTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the invention. Specificexamples of components and arrangements are described below to simplifythe present disclosure. These are, of course, merely examples and arenot intended to be limiting. For example, the formation of a firstfeature over or on a second feature in the description that follows mayinclude embodiments in which the first and second features are formed indirect contact, and may also include embodiments in which additionalfeatures may be formed between the first and second features, such thatthe first and second features may not be in direct contact.

In addition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed. Variousfeatures may be arbitrarily drawn in different scales for the sake ofsimplicity and clarity.

Furthermore, spatially relative terms, such as “beneath,” “below,”“lower,” “above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The device may be otherwise oriented (rotated 90 degrees orat other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

It should be understood that additional operations can be providedbefore, during, and after the method described below, and some of theoperations described can be replaced or eliminated for other embodimentsof the method.

Embodiments of an improved indirect bonding method of orthodonticbrackets are provided. The following embodiments relate in particular toan improved method of producing a positioning guide used for assistingthe positioning of an orthodontic bracket on each tooth of a patient.The improved indirect bonding method facilitates precise and easypositioning of orthodontic brackets. Other advantages will be explainedlater. Some variations of the embodiments are described. Throughout thevarious views and illustrative embodiments, common elements use the samereference number.

FIG. 1 is a simplified flow chart of an indirect bonding method 10, inaccordance with some embodiments. For illustration, the flow chart willbe described along with the drawings shown in FIGS. 2 to 9 . Some of thedescribed operations can be replaced or eliminated in differentembodiments. Alternatively, some operations may be added in differentembodiments.

The indirect bonding method 10 begins with operation S1, in which anoriginal dental model M1 and a setup (or desired) dental model M2 of adental arch (e.g., a lower or upper dental arch) of a patient areprovided, as shown in FIG. 2 . The original dental model M1 reproducesthe dentition state of the dental arch of the patient before orthodontictreatment. For example, a dentist may take an impression of thepatient's dental arch and digitally scan the impression or may makedirectly an intraoral scan of the patient's mouth. The original dentalmodel M1 is then be made from the impression or the intraoral scan imageusing techniques well known in the art (e.g., gypsum molding). The setupdental model M2 has the desired dentition state of the patient's dentalarch after orthodontic treatment. For example, the setup dental model M2can be derived from the original dental model M1 by manually moving eachtooth of the original dental model M1 to the desired orientation orposition (i.e. the orientation or position after orthodontic treatment).Alternatively, a digital setup dental model can be created by a computersimulated approach, and the setup dental model M2 is made from thedigital model using techniques well known in the art (e.g., gypsummolding).

It should be appreciated that after determining the installing positionof each orthodontic bracket on the setup dental model M2 having thedesired dentition state, the orthodontic brackets are transferred andinstalled to the actual teeth of the patient before the actualorthodontic treatment. Therefore, the installing positions of theorthodontic brackets become ideal. The setup dental model M2 having suchthe desired dentition state can be used because the indirect bondingmethod 10 embodiments described below uses a positioning guide and canaccurately reproduce the installing positions of the orthodonticbrackets determined on the setup dental model M2 on the actual teeth ofthe patient.

In some embodiments, a separating material is applied to the setupdental model M2 and/or the original dental model M1 prior to positioningthe orthodontic brackets on the dental model(s). The separating materialhelps make removing the orthodontic brackets and other integratedcomponents (which will be described later) from the dental model(s). Theapplication of a separating material is well-known in the art and isthus not discussed here.

The indirect bonding method 10 continues to operation S2, in which anorthodontic archwire W engaged with a set of orthodontic brackets isinstalled on the setup dental arch M2, as shown in FIG. 2 (theorthodontic brackets are not shown in FIG. 2 for simplicity). Theorthodontic archwire W can be fixed in place on the setup dental arch M2via supports P. In some cases, if each orthodontic bracket is to bebonded to the tongue side surface of each tooth of the patient for thesubsequent actual orthodontic treatment, the orthodontic archwire W isplaced at the tongue side M21 of the setup dental arch M2, as shown inFIG. 2 . In some unillustrated cases, if each orthodontic bracket is tobe bonded to the cheek side surface of each tooth of the patient for thesubsequent actual orthodontic treatment, the orthodontic archwire W isplaced at the cheek side M22 of the setup dental arch M2. Theorthodontic archwire W is resilient (e.g., made of shape memory alloy(SMA) or other available metallic materials) and formed to match thesetup dental arch M2. The positions of the orthodontic brackets aredetermined by engaging the orthodontic brackets to the fixed orthodonticarchwire W.

FIG. 3 is a schematic side view of an orthodontic bracket B, inaccordance with some embodiments. In some embodiments, the usedorthodontic bracket B includes a main body 11 having a centrallongitudinal groove 12 for receiving the orthodontic archwire W (notshown in FIG. 3 for simplicity). The main body 11 further has upper andlower tie wings 14 defining wire tie-down grooves 16. A bracket base 18is integrated with the main body 11 and has a bonding surface 20 forbonding the orthodontic bracket B to the tooth surface (e.g., the tongueor cheek side surface) of a tooth of the patient. While the orthodonticarchwire W is installed on the setup dental arch M2 in operation S2, thebonding surface 20 of each orthodontic bracket B faces the tooth surface(e.g., the tongue or cheek side surface) of a corresponding tooth of thesetup dental arch M2 to be bonded (see FIG. 4 ). The above orthodonticbracket B is merely an illustrative example, and other types or shapesof orthodontic brackets can also be used. The orthodontic bracket B maybe made of or comprise ceramic, metal, or other available materials(such as polycarbonate).

The indirect bonding method 10 continues to operation S3, in which aspace between the bonding surface 20 of each orthodontic bracket B andthe tooth surface (e.g., the tongue side surface T1) of thecorresponding tooth T of the setup dental model M2 is filled with a padmaterial 30, as shown in FIG. 4 . In some embodiments, a primer layer 32is coated on the bonding surface 20 of the orthodontic bracket B priorto the formation of the pad material 30 in order to facilitate theadhesion of the pad material 30 to the bonding surface 20. The primerlayer 32 may be chemical-cured, light-cured, or dual-cured prior to thenext step.

After the coated primer layer 32 has been cured, a pad material 30 iscoated over the primer layer 32 to fill a space between each orthodonticbracket B and the corresponding tooth T of the setup dental model M2.Then, the coated pad material 30 is cured to temporarily adhere theorthodontic bracket B to the tooth surface of the corresponding tooth Twhich is previously coated with a separating material. As such, theinstalling position of each orthodontic bracket B on the setup dentalmodel M2 (as well as on the actual teeth of the patient) is determined.The orthodontic archwire W is removed after the orthodontic brackets Bare bonded to the teeth of the setup dental model M2, in someembodiments.

In some embodiments, the primer layer 32 and the pad material 30 aremade of one or more dental restorative materials. These dentalrestorative materials are known in the art and containphotopolymerizable resins such as acrylate or methacrylate resins (forexample, ethoxylated bisphenol A dimethacrylate (EBPADMA); urethanedimethacrylate (UDMA) and triethylene glycol dimethacrylate (TEGDMA));polymerization initiators (for example, camphorquinone (CQ));polymerization accelerators (for example, ethyl 4-dimethylamino benzoate(EDMAB)); filler particles (for example, silica and glasses); andadditives (for example, blue or ultraviolet-light absorbers,anti-oxidants, plasticizers, and the like). Alternatively, glass-ionomermaterials (based on the reaction of silicate glass powder that isusually a fluoroaluminosilicate, and polyalkeonic acid) may be usedalone or in combination with such photopolymerizable resins. In someembodiments, in order to fill the space between the bonding surface andthe tooth surface, the pad material 30 has higher viscosity than theprimer layer 32. In some other embodiments, the primer layer 32 can alsobe omitted.

The indirect bonding method 10 continues to operation S4, in which arigid guiding structure 40 consisting of two separated parts (i.e. witha gap therebetween) is formed, as shown in FIG. 5 . The rigid guidingstructure 40 is a part of a positioning guide PG (see FIG. 6 ) providedin the disclosure used for transferring the orthodontic bracket B to theactual tooth of the patient. The term “rigid guiding structure” usedherein indicates that it is inflexible and does not deform duringtransfer of the orthodontic bracket B.

In some embodiments as shown in FIG. 5 , the formed rigid guidingstructure 40 includes a first part 41 fitting and covering a part or theentire outer surface 21 (see also FIG. 3 ) of an orthodontic bracket B,wherein the outer surface 21 is opposite to the bonding surface 20. Theformed rigid guiding structure 40 further includes a second part 42fitting and covering the occlusal surface T2 of a corresponding tooth Tof the setup dental model M2. In some embodiments, the second part 42further extends to cover a part of the opposing tooth surface (e.g., thecheek side surface T3) of the tooth T of the setup dental model M2, asshown in FIG. 5 . With the above configurations, each orthodonticbracket B can be accurately installed on each actual tooth of thepatient by only fitting the second part 42 to each tooth of the patientso as to cover the occlusal surface, which will be further describedlater.

In some embodiments, the second part 42 of the rigid guiding structure40 further has a handle portion 421 which has a greater thickness thanthe other portions of the second part 42, as shown in FIG. 5 . Thehandle portion 421 is formed as an extension portion of the rigidguiding structure 40 so as to facilitate manipulation and provide aconvenient area for connecting adjacent rigid guiding structures 40,which will be further described later. The handle portion 421 may have asubstantially circular cross-section, in some embodiments. However,other cross-sectional shapes can also be used as long as the aboveeffects can be achieved.

In some embodiments, the rigid guiding structure 40 is made of orcomprises a photopolymerizable material, such as a DURALAY™ resin, adental tray resin, or another available photopolymerizable resin. Toform the rigid guiding structure 40, a photopolymerizable material inliquid state is applied (e.g., by injection) to the outer surface 21 ofan orthodontic bracket B and the occlusal surface T2 of thecorresponding tooth T of the setup dental model M2. Then, thephotopolymerizable material is cured via appropriate light energy. Thus,both mechanical and chemical bonding of the rigid guiding structure 40can occur. The rigid guiding structure 40 may be transparent,translucent, or colored, in some examples. In some embodiments, theformed rigid guiding structure 40 does not extend to engage the undercutof the orthodontic bracket B, as shown in FIG. 5 .

The indirect bonding method 10 continues to operation S5, in which aflexible linking structure 50 is formed to connect the first part 41 andthe second part 42 of the rigid guiding structure 40, as shown in FIG. 6. The flexible linking structure 50 is also a part of a positioningguide PG provided in the disclosure used for transferring theorthodontic bracket B to the actual tooth of the patient. The terms“flexible linking structure” used herein indicates that it is flexibleand retains elasticity (for example, the flexible linking structure 50may flex or deform under pressure, and return to its original shape whenthe pressure is released). This helps the formed positioning guide PG tobe removed later from the orthodontic bracket B, which will be furtherdescribed later.

In some embodiments as shown in FIG. 6 , the flexible linking structure50 is formed on the tooth surface (e.g., the tongue side surface T1) ofthe tooth T of the setup dental model M2 bonded with the orthodonticbracket B to integrate with the first part 41 and the second part 42 ofthe rigid guiding structure 40. In some embodiments, before forming theflexible linking structure 50, a barrier layer 52 (see FIG. 6 ) ispreviously formed in order to prevent the subsequently formed flexiblelinking structure 50 from integrating with the pad material 30. Thebarrier layer 52 may be made of or include dental wax or silicone toensure separation.

In some alternative embodiments as shown in FIG. 6A, the flexiblelinking structure 50 further has a portion formed in a region of thesecond part 42 of the rigid guiding structure 40 on the opposing toothsurface (e.g., the cheek side surface T3) of the tooth T of the setupdental model M2. That is, in addition to the tooth surface bonded to theorthodontic bracket B, the flexible linking structure 50 also contactsand conforms to the opposing tooth surface without an orthodonticbracket B. With the above configuration, the flexible linking structure50 allows the positioning guide to flex at the appropriate locations soas to facilitate the mounting and removal from the actual tooth of thepatient.

In some embodiments, the flexible linking structure 50 is made of orcomprises a photopolymerizable material, such as an ethylene vinylacetate (EVA) resin or another available photopolymerizable resin. Toform the flexible linking structure 50, a photopolymerizable material inliquid state is applied (e.g., by injection) to a gap between the firstpart 41 and the second part 42 of the rigid guiding structure 40 and/ora previously formed recess (see FIG. 6A) in the second part 42. Then,the photopolymerizable material is cured via appropriate light energy.Thus, both mechanical and chemical bonding of the flexible linkingstructure 50 can occur. The flexible linking structure 50 may betransparent, translucent, or colored, in some examples. In someembodiments, the formed flexible linking structure 50 does not extend toengage the undercut of the orthodontic bracket B, as shown in FIG. 6 .

In some embodiments as shown in FIG. 7 , after the flexible linkingstructure 50 is formed, a rigid linking structure 54 is further formedadjacent to the flexible linking structure 50 to connect the first part41 and second part 42 of the rigid guiding structure 40 so as to enhancethe structural integrity and strength of the formed positioning guidePG. The rigid linking structure 54 may be harder than the flexiblelinking structure 50. For example, the rigid linking structure 54 andthe rigid guiding structure 40 may comprise the same material (e.g., aDURALAY™ resin). Alternatively, the rigid linking structure 54 and therigid guiding structure 40 may comprise similar materials (for example,one of which comprises a DURALAY™ resin, and the other comprise a dentaltray resin). After the rigid linking structure 54 is applied over theflexible linking structure 50 and parts of the first part 41 and secondpart 42, it is cured via appropriate light energy.

Through the above operations, a positioning guide PG (see FIGS. 6 to 8 )including at least a rigid guiding structure 40 with two separated partsand a flexible linking structure 50 is formed to integrate with eachorthodontic bracket B temporarily bonded to the setup dental model M2.Since the tooth surface of each tooth T of the setup dental model M2 ispreviously coated with a separating material, individual orthodonticbrackets B and the integrated positioning guides PG (as well as theintegrated pad materials 30) can be easily removed.

The indirect bonding method 10 continues to operation S6, in whichindividual orthodontic brackets and the integrated positioning guides PGare transferred to the original dental model M1 obtained in operationS1, as shown in FIG. 8 (the orthodontic brackets are not shown due tolimited viewing angle). Each orthodontic bracket and the integratedpositioning guide PG may be placed or positioned on the teeth of theoriginal dental model M1 in a manner similar to the placement on theteeth of the setup dental model M2 (for example, as shown in FIG. 7 ).Then, several adjacent individual positioning guide PG are joined at thehandle portions 421 of the second parts 42 using holding parts 60 toform a positioning guide unit PG′. The holding parts 60 may comprise thesame material as the rigid guiding structure 40 discussed above, but anyother suitable dense, accurate, and non-shrinking material that can behandled without distortion or temperature changes can also be used forthe holding parts 60, as well as the rigid guiding structures 40 and therigid linking structures 54. For the flexible linking structure 50, anyother suitable high strength, elastic, and highly durable material thatconforms to the shape of the dental model without warp after forming anddistortion after removal, can also be used.

In some embodiments as shown in FIG. 8 , three positioning guide unitsPG′ are formed, one of which covers several anterior teeth, anothercovers several left teeth, and another covers several right teeth of theoriginal dental model M1. However, the invention is not limited to theseembodiments, and one or more positioning guide units PG′ each consistingof any number of the positioning guides PG may also be formed asdesired. The tooth surface of each tooth of the original dental model M1is also previously coated with a separating material to facilitateremoval of the positioning guide units PG′ and the integratedorthodontic brackets B.

The indirect bonding method 10 continues to operation S7, in whichindividual positioning guide units PG′ and the integrated orthodonticbrackets B are transferred to the actual teeth AT of the correspondingdental arch of the patient for bonding, as shown in FIG. 9 . Asdiscussed above, each orthodontic bracket B can be accurately installedon each actual tooth AT of the patient by only fitting the second part42 of the rigid guiding structure 40 to each actual tooth AT of thepatient so as to cover the occlusal surface, as shown in FIG. 9 . Theshape and orientation of the positioning guide PG and the integratedorthodontic bracket B are maintained (due to the rigidity of the rigidguiding structure 40) when transferred to the actual tooth of thepatient, thereby providing precise positioning. Moreover, eachpositioning guide unit PG′ is formed to fit multiple adjacent teeth ofthe original dental model M1 reproducing the dentition state of thepatient, and therefore it maintains better positioning accuracy whentransferring a set of orthodontic brackets B to the corresponding actualteeth AT of the patient. A bonding adhesive (not shown) is previouslycoated over the pad material 30 on the bonding surface 20 of eachorthodontic bracket B and/or the tooth surface (e.g., the tongue sidesurface T1) of the corresponding actual tooth AT.

In a method of transferring predetermined bracket positions from thedental models onto the dentition using a positioning guide, the problemof maintaining positional accuracy must be addressed. In terms ofpositional accuracy, the position in the occlusal to gingival directionis more easily maintained than the position in the mesial to distaldirection. In the case of lingual brackets, adjacent teeth in a crowdeddentition introduces new undercuts that must be worked around toproperly seat the positioning guide onto the dentition. If thepositioning guide is a single structure made of a flexible material, itmust stretch, primarily in the mesial to distal direction, to workaround the crowded adjacent teeth. However, the stretched positioningguide may not completely recover its form and thus lose positionalaccuracy. To maintain positional accuracy in the mesial to distaldirection, the present invention provides a method of forming a rigidstructure that links a rigid guiding structure, a rigid linkingstructure, and holding part that holds adjacent positioning guides in aunit. In addition, the section of the dentition can be carefullyselected to use a positioning guide unit with minimal stretching. Morespecifically, when one positioning guide PG is positioned on an actualtooth AT, the rigid guiding structure 40, the rigid linking structure54, and the holding part 60 connected to an adjacent positioning guidePG together maintains positional accuracy for the placement of theintegrated orthodontic bracket B on the actual tooth AT in the mesial todistal direction, which improves upon conventional positioning guidesthat use entirely or primarily EVA or other flexible materials in itsoverall structure.

After bonding the orthodontic bracket B to the corresponding actualtooth AT via the bonding adhesive, the positioning guide PG/positioningguide unit PG′ can be easily and cleanly removed by being separated fromthe orthodontic bracket B and the actual tooth AT (as indicated by thearrows in FIG. 9 ). Being flexible and resilient, the flexible linkingstructure 50 helps removing the positioning guide PG/positioning guideunit PG′. On the other hand, the rigid guiding structure 40 being rigidhas less chance for residues to remain on the orthodontic bracket B andthe actual tooth AT. The shape of the positioning guide PG, especiallywith an extended handle portion 421, is easier to handle and manipulate.

In some embodiments, the entire positioning guide unit PG′ withconnected positioning guides PG can be removed as a whole.Alternatively, individual positioning guides PG are separated by cuttingaway the holding parts 60 (see FIG. 8 ), and each positioning guide PGcan then be removed.

In some further embodiments, an orthodontic archwire (not shown) isprovided to connect the orthodontic brackets B which have been firmlybonded to the actual teeth of the patient through the indirect bondingmethod 10 described above. The orthodontic archwire is resilient and ispre-shaped to match the setup dental model M2. As such, the orthodonticarchwire exerts forces on the teeth through the orthodontic brackets Bto bring the teeth into alignment with the pre-shaped form of theorthodontic archwire for orthodontic treatment.

As described above, the improved indirect bonding method provided in thedisclosure facilitates precise and easy positioning of orthodonticbrackets. Since the orthodontic brackets can be installed at properpositions on the teeth of the patient while no deviation occurs duringtransfer of the positioning guide onto the dentition, the idealorthodontic treatment effect can be achieved.

Although embodiments of the present disclosure and their advantages havebeen described in detail, it should be understood that various changes,substitutions and alterations can be made herein without departing fromthe spirit and scope of the disclosure as defined by the appendedclaims. For example, it will be readily understood by those skilled inthe art that many of the features, functions, processes, and materialsdescribed herein may be varied while remaining within the scope of thepresent disclosure. Moreover, the scope of the present application isnot intended to be limited to the particular embodiments of the process,machine, manufacture, composition of matter, means, methods and stepsdescribed in the specification. As one of ordinary skill in the art willreadily appreciate from the disclosure of the present disclosure,processes, machines, manufacture, compositions of matter, means,methods, or steps, presently existing or later to be developed, thatperform substantially the same function or achieve substantially thesame result as the corresponding embodiments described herein may beutilized according to the present disclosure. Accordingly, the appendedclaims are intended to include within their scope such processes,machines, manufacture, compositions of matter, means, methods, or steps.In addition, each claim constitutes a separate embodiment, and thecombination of various claims and embodiments are within the scope ofthe disclosure.

What is claimed is:
 1. A dental appliance, comprising: an orthodonticbracket having a bonding surface for adhering to a tooth of a patient;and a positioning guide configured to position the orthodontic bracketon the tooth of the patient, wherein the positioning guide comprises: arigid guiding structure including a first part and a second partseparated from each other, wherein the first part is configured to covera part of an outer surface of the orthodontic bracket opposite to thebonding surface, and the second part has a shape matching an occlusalsurface of the tooth, and wherein the first part and the second part ofthe rigid guiding structure are separated, and the first part of therigid guiding structure does not extend to engage an undercut of theorthodontic bracket; a flexible linking structure configured to connectthe first part and the second part of the rigid guiding structure,wherein the flexible linking structure fills a gap between the firstpart of the rigid guiding structure and a side of the orthodonticbracket on a first side, and the second part of the rigid guidingstructure on a second side, wherein the flexible linking structure alsodoes not extend to engage an undercut of the orthodontic bracket,wherein the rigid guiding structure is inflexible and the flexiblelinking structure is elastic and retains form, and wherein the rigidguiding structure is harder than the flexible linking structure; and arigid linking structure adjacent to the flexible linking structure toconnect the first part and the second part of the rigid guidingstructure, wherein the rigid linking structure is harder than theflexible linking structure.
 2. The dental appliance as claimed in claim1, wherein the second part of the rigid guiding structure includes ahandle portion having a greater thickness than other portions of thesecond part.
 3. The dental appliance as claimed in claim 2, furthercomprising a plurality of the orthodontic brackets, a plurality of thepositioning guides, and at least one holding part configured tointegrate a number of the adjacent positioning guides at the handleportions of the plurality of the positioning guides.
 4. The dentalappliance as claimed in claim 3, wherein the at least one holding partand the rigid guiding structure comprise a same material.
 5. The dentalappliance as claimed in claim 1, wherein the rigid guiding structurecomprises a photopolymerizable material.
 6. The dental appliance asclaimed in claim 5, wherein the photopolymerizable material of the rigidguiding structure comprises dental tray resin.
 7. The dental applianceas claimed in claim 1, wherein the flexible linking structure comprisesa photopolymerizable material.
 8. The dental appliance as claimed inclaim 7, wherein the photopolymerizable material of the flexible linkingstructure comprises ethylene vinyl acetate (EVA) resin.
 9. The dentalappliance as claimed in claim 1, wherein the flexible linking structureis formed to contact with a side surface of the tooth.
 10. The dentalappliance as claimed in claim 1, wherein the rigid linking structure andthe rigid guiding structure comprise a same material.
 11. The dentalappliance as claimed in claim 1, wherein the first part of the rigidguiding structure does not extend into an archwire groove on the outersurface of the orthodontic bracket.
 12. The dental appliance as claimedin claim 2, wherein the handle portion has a circular cross-section.